The present invention relates to an electric resistance welding machine characterized by features which ensure a considerable versatility thereof, in the sense of its adaptability to various types of work, and a high productivity under the best conditions of efficiency.
In the welding machines adapted selectively to perform different welding operations, comprising a workpiece holding lower bracket, an upper bracket and an implement holding head movable in the upper bracket, the free height between the brackets must be considerable so as to allow, when necessary, the use of welding implements of considerable height. This has the disadvantage of rendering more extensive the welding circuit connected to the transformer mounted within the upper bracket or near it, and involving an unnecessary increase of the impedance and hence power losses in the secondary circuit which, when the implement is in the working position, could have much smaller dimensions.
Another disadvantage of the known welding machines of the type provided with a movable (translating or rotatable) workpiece-holding table consists in the difficulty of connecting the table to the secondary welding circuit in a way suitable for the transmission of the high currents involved.